A randomized controlled trial to determine the effect of triptorelin on reduction of prostate volume preradiotherapy compared with standard therapy (goserelin).

30 Background: Hormone therapy in combination with radiotherapy is a curative treatment option for prostate cancer (CaP). Neoadjuvant goserelin is known to reduce prostate gland volume by about 26%, such that radiotherapy treatment volumes are smaller, reducing the risk of damage to bladder and rectum. Triptorelin is 100 times more potent than native LHRH and has a longer half life than both native LHRH and goserelin. This study evaluated the equivalence of cytoreductive efficacy of neoadjuvant triptorelin and goserelin. Methods: Seventy-onepatients with localized CaP who have chosen radical radiotherapy had been randomized by stratified block design, toreceive either triptorelin (n=37) or goserelin (n=34) with bicalutamide cover. Prostate volume was measured at baseline and 14 weeks after start of therapy on transrectal ultrasound (TRUS). PSA, testosterone levels, and EQ5D, QLQ-PR25, QLQ-C30 questionnaires were completed at baseline, 6, 10, and 14 weeks after start of therapy. All the patients had subsequent radical radiotherapy and followed up as per departmental protocol. Changes in TRUS volume and time to castrate levels of testosterone were evaluated. Results: The mean (±S.D) baseline prostate volume in the goserelin and triptorelin groups was 38.1(±12.8) cc and 39.4(±17.5) cc, respectively. The mean (±S.D) reduction in the prostate volume after 14 weeks of goserelin and triptorelin was 36.8(±18.4)% and 32.5(±20.9)%, respectively (p=0.36: Analysis of Covariance). Twenty-nine out of 34 in the goserelin group and 33 out of 37 patients in the triptorelin group achieved castrate levels of testosterone (£0.5nmol/L). The median time to castration was 6.1 (95% CI: 5.8-6.5) and 6.4 (95% CI: 5.9-10.0) weeks for goserelin and triptorelin, respectively (p=0.72: log rank). Conclusions: Goserelin and triptorelin both caused a reduction inprostate volume and achieved castrate levels of testosterone. The cytoreductive efficacy of neoadjuvant triptorelin was equivalent (non-inferior) to that of goserelin. To our knowledge, this is the first reported prospective randomized data demonstrating the equivalence of goserelin and triptorelin in the neoadjuvant setting. Clinical trial information: 2008-007028-25.